http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51155
Bug #: 51155
Summary: sizeof and sizeof... in template partial
specialization
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: pubb...@gmail.com
-std=c++11
gcc version 4.7.0 20111112 (experimental) (GCC)
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14.5.5.8 of n324 states:
"A partially specialized non-type argument expression shall not involve a
template parameter of the
partial specialization except when the argument expression is a simple
identiļ¬er."
From what I understand, this seems to be broken when using sizeof:
---
template <int a, int b>
struct foo { };
// partial specializations:
template <int a>
struct foo<a, 0> { }; // correct and compiles
template <int a>
struct foo<a + 1, 0> { }; // not correct and doesn't compile
template <int a>
struct foo<sizeof(a), 0> { }; // not correct and doesn't compile
// due to 'a' not being used
template <int a>
struct foo<sizeof(a), a> { }; // not correct and compiles
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Additional bugs when using sizeof.. with a variadic template
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template <int n, int... xs>
struct foo { };
// partial specialization:
template <int... xs>
struct foo<sizeof...(xs), xs...> { }; // not correct and doesn't compile
// although it should if sizeof is
allowed
template <int... xs>
struct foo<sizeof(xs), xs...> { }; // not correct and compiles
// sizeof(xs) evaluates to sizeof(int)
// which is incorrect
---
